Condensation polymers
Another type of polymerisation reaction is known as condensation polymerisation. In such a reaction a small molecule, such as water, is given off for each monomer that attaches to the polymer chain. Most natural polymers, such as proteins and DNA, are condensation polymers.
Proteins, for example, are condensation polymers. The reaction that links amino acids (monomers) together is shown on the right. For every amino acid that attaches to the protein chain a water molecule is ejected. Notice how each amino acid has two functional groups, a carboxyl (COOH) and an amino (NH2).
Many condensation polymers are also man made. The reaction on the right shows Dacron being formed. Dacron is formed from two different monomers, ethylene glycol and terephthalic acid. A polymer formed from two different monomers is known as a copolymer. Note that each monomer has two functional groups through which the polymer, known as a polyester, can grow. This polymer is widely used in industry for the manufacture of clothing.

Consider the compounds shown on the right.

1) Which compound can act as a monomer, when used on its own, to form a condensation polymer?

2) What small molecule will be given off as each monomer links to the chain.

3) Which two compounds can act as monomers to form a condensation polymer?

4) What small molecule is given off when these two compounds react?

5) Draw the structural formula of the polymer formed in Q4. Solution